A Virtual Private Network (VPN) utilizes a public or private communications network to conduct private communications. Traditionally, a company or other customer that wanted to build a wide-area network had to provide for its own dedicated lines between each node to provide the connectivity. Such solutions are, however, generally expensive and inflexible. During the last years, the concept of VPNs has evolved rapidly. VPNs offer a solution, where a communications network is shared between many customers, but where the communication of each customer is virtually separated. VPN technology is often based on the idea of tunneling. Network tunneling involves establishing and maintaining a logical network connection. On this connection, packets are encapsulated within some other base or carrier protocol. They are then transmitted between VPN client and server and eventually de-encapsulated on the receiver side. Authentication and encryption assists in providing security.
A tendency is that the number of network nodes that form a VPN grows fast, which results in large complex network structures and topology. This is caused, partly because of the increasing traffic on VPNs and partly on that the VPNs are requested to cover larger and larger geographical areas. Communication networks providing VPNs having nodes at all continents are present today. However, the more nodes and the more traffic that is to be transmitted, the more complex the configuration of VPNs becomes. Conventionally, a VPN is created according to an agreement between a network operator and a customer. The location of the nodes, the quality of service and other conditions are agreed on and a programmer at the operator sets up the configuration manually or by consulting configuration aid tools. When having more and more complex communications networks, such configuration becomes more and more complex and time consuming. Furthermore, when a customer wants to modify its VPN, the entire procedure has to be repeated.
When setting up VPNs in a network, different technologies can also be used. Each technology has its own benefits and drawbacks and its own way of configuring the VPNs. There is no general VPN architecture that is independent of VPN technology.